1. Field of the Invention
The present invention relates to a stabilizer for motor road vehicles, particularly of the type capable of changing the roll rigidity of the associated vehicle depending upon variations of running condition.
2. Description of the Prior Art
A motor vehicle stabilizer of the above mentioned type is well known in the art as is, for example, disclosed in the Japanese Provisional Patent Publication No. 57-66009 and the Japanese Utility Model Publication No. 59-129613.
In this type of stabilizer, a channel-shaped stabilizer bar, which has a pair of arm portions connected to suspension arms carrying left and right vehicle wheels, is divided into two parts, a left-hand part and right-hand part. One of the parts is connected with a piston and the other with a cylinder. The piston is movable in the cylinder and defines a pair of hydraulic chambers at the opposite ends thereof. The hydraulic chambers are communicated with each other through a conduit in which a control valve is disposed to establish or obstruct communication between the hydraulic chambers in such a manner that a softer ride is obtained upon high-speed straight-ahead running and an increased roll rigidity upon turning.
A disadvantage of the above mentioned stabilizer is that it is complicated in structure, particularly when used in a four-wheel-drive vehicle, and it is not highly reliable in operation since the sealing members utilized in the hydraulic cylinder are likely to be deteriorated to prevent the stabilizer from effecting a desired stabilizing action. Furthermore, the above mentioned stabilizer tends to increase the unsprung weight of the vehicle.
Another stabilizer of the above mentioned kind is disclosed in the Japanese Provisional Patent Publication No. 59-34910.
In this stabilizer, the free ends of the stabilizer bar are connected through coil springs to suspension arms. The compressed state of the coil springs is manually controlable to change the effectiveness of the stabilizer.
A disadvantage of this latter stabilizer is that the effectiveness of the stabilizer cannot be changed so largely and it cannot provide a highly reliable operation due to its cam structure.